Rapid typing of Mannheimia haemolytica major genotypes 1 and 2 using MALDI-TOF mass spectrometry

Abstract

Bovine respiratory disease (BRD) is one of the most costly diseases to cattle production throughout the globe, and losses in the US are estimated at one billion dollars annually. Mannheimia haemolytica is the most commonly detected bacterial agent associated with BRD. Recently, whole genome sequencing was employed on 1,133 M. haemolytica isolates from North American cattle and a nucleotide polymorphism typing system was developed. Two major genotypes were discovered (1 and 2). Genotype 1 M. haemolytica were mostly isolated from the nasopharynx of cattle without BRD. In contrast, genotype 2 M. haemolytica predominantly associated with the lungs of cattle with BRD and integrative conjugative elements that contained antimicrobial resistance determinants. The objective of this study was to develop a rapid matrix-assisted laser desorption/ionization- time of flight mass spectrometry (MALDI-TOF MS) assay for the detection of M. haemolytica genotypes 1 and 2. MALDI-TOF MS is an emerging technology in diagnostic microbiology and is most frequently used for bacterial identification.